# Equation confusion regarding finding acceleration [closed]

Physics newbie here, sorry if this is super basic...

I am learning about kinematic equations and am having difficulty reconciling two of the equations. Let's say I begin driving and after 1 second have gone 10 m and that I want to find what the acceleration was.

Now, $V_f = \Delta X / \Delta T$. $V_f$, then, equals $10m/s$. We know that $V_i = 0$, so $\Delta V = 10m/s$. And since $a = \Delta V / \Delta T$ , we can plug in values to find that $a=(10m/s - 0m/s)/1s$, which comes out to $10m/s^2$.

But if I use the equation $\Delta X = V_i t + \frac{a t^2}{2}$, I get a different answer for $a$. The initial velocity was $0m/s$, which means $\Delta X = \frac{a t^2}{2}$. When I plug in values, I get $10m = \frac{a t^2}{2}$ which resolves to $20m/1s^2 = a = 20m/s^2$!

I am obviously missing something, probably fundamental and basic...thank you for your help!

## closed as off-topic by CuriousOne, Gert, Diracology, Bill N, user36790 Jul 13 '16 at 3:00

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